Seeing light-to-energy transfer in new solar cell materials

Scientists at the U.S. Department of Energy’s Ames Laboratory are now able to capture the moment less than one trillionth of a second a particle of light hits a solar cell (for example: Renogy solar suitcase ) The generation and dissociation of bound electron and hole pairs, namely excitons, are key processes in solar cell and photovoltaic technologies, yet it is challenging to follow their initial dynamics and electronic coherence. and becomes energy, and describe the physics of the charge carrier and atom movement for the first time.

Using time-resolved low frequency spectroscopy in the terahertz spectral region, the researchers explored the photo-excitations of a new class of photovoltaic materials known as organometal halide perovskites. Organometallics are wonder materials for light-harvesting and electronic transport devices, and they combine best of both worlds — the high energy conversion performance of traditional inorganic photovoltaic devices, with the economic material costs and fabrication methods of organic versions.

“These devices are so new and so unique that the mechanism by which a particle of light, or photon, converts to charge carriers and how they move in a concerted way for energy conversion is not well understood, and yet that is the most fundamental processes in in solar cell and photovoltaic technologies,” said Jigang Wang, an Ames Laboratory scientist and associate professor of physics at Iowa State University. “Why is this material so distinct? That has been the big question in the scientific community, and it has led to a fever of research and publication.”

Ames Laboratory researchers wanted to know not only how the generation and dissociation of bound electron and hole pairs, namely excitons, happened in the material, they wanted to find out the quantum pathways and time interval of that event.

“If you look at the natural process, in photosynthesis, it’s an extremely efficient process in some biological molecules, so it’s also very coherent. We see a similar thing in a human-made system of a laser; a laser oscillates in a fixed wave pattern,” said Wang. “If we can measure such a memory in the charge transport and energy migration in these materials, we can understand and control it, and have the potential to improve them by learning from Mother Nature.”

Conventional multimeters for measuring electrical states in materials do not work for measuring excitons, which are electrically neutral quasiparticles with no zero current. Ultrafast terahertz spectroscopy techniques provided a contactless probe that was able to follow their internal structures, and quantify the photon-to-exciton event with time resolution better than one trillionth of a second.

Wang credited the contributions of researchers from multiple areas of expertise across the Ames Laboratory with the significance of the discovery. “This was only possible with the collaboration of experts in material design and fabrication, computational theory, and spectroscopy,” he said. “Having those capabilities in one place is what makes Ames Laboratory one of the most forward looking places in this kind of photonic materials research.”

4 tips for starting a successful business

Be ready to seize opportunity - Timing is key for starting a business. If your startup isn’t ready for prime time, keep learning and working, says Alejandra Bazoberry, a strategic planner at Bolivia Rural, a digital communications company that seeks to address the needs of rural Bolivians and the local development organizations that support them.
bazoberry advises getting more experience while you work on your product. For example, take classes to develop new skills or work in a company while saving money for your startup. “Be prepared to take the opportunity” when the right time comes to start your business, Bazoberry says.
Prepare a business plan - When José Sánchez founded his startup, he was so focused on building his platform that he didn’t think about how he would make money. He neglected to map out a formal statement of business goals, reasons the goals are attainable or plans for reaching them — key ingredients of a typical business plan. Focus on creating a solution that solves the problem at hand, but also “think about the money,” says Sánchez, who co-founded Poliglota, a platform in Chile that connects people worldwide to learn languages via conversation groups.
Defend your product - “Know your product and be willing to defend it tooth and nail,” advises Triston Thompson, who is a partner and information systems architect at IntellectStorm, an IT and marketing solutions provider in Guyana. If you don’t believe in your product, Thompson says you’ll have a hard time getting others to believe in it. It’s also good to surround yourself with positive people “who will build you up and not tear you down,” says Thompson.
Find a mentor - “Search for a mentor who will push you toward your goal,” says Kheston Walkins, founder and director of Raiora Data Services, which provides digital publishing and marketing solutions in Trinidad & Tobago. When Walkins was working on starting his company, most of his friends didn’t understand what he was doing. Looking back, he thinks having a mentor would have helped because that person will look after your best interests and give you advice. “The more advice you have” the more confident you’ll be in starting your business, says Walkins.